1. Field
One or more exemplary embodiments relate generally to flat panel displays. More specifically, one or more exemplary embodiments relate to an organic light-emitting display apparatus and a method of driving the same.
2. Description of the Related Art
Organic light-emitting display apparatuses use an organic light-emitting diode, the luminance of which is controlled by a current or a voltage. The organic light-emitting diode includes a positive electrode layer and a negative electrode layer forming an electric field, and an organic emission material which emits light due to the electric field.
A pixel in an organic light-emitting display apparatus includes the organic light-emitting diode, a driving transistor which controls an amount of current supplied to the organic light-emitting diode, and a switching transistor which transfers a data voltage for controlling an emission amount of the organic light-emitting diode to the driving transistor.
The organic light-emitting display apparatus may be driven by a driving method in which a deviation from a threshold voltage of the driving transistor is compensated for and then a data signal is input to the pixels. After the compensation of the threshold voltage, an anode voltage of the organic light-emitting diode may gradually increase due to effects of a noise current, etc. When the anode voltage increases, a gate voltage of the driving transistor also gradually increases due to a capacitive coupling between a gate electrode and a drain electrode of the driving transistor. Since pixels receive the data signal at different points in time according to locations of the pixels, the rise in the gate voltage produces differing effects on the pixels according to the locations of the pixels. As a result, an image is non-uniformly displayed.
In order for the organic light-emitting diode to emit light, the driving transistor needs to continually maintain an on state, and as time passes, a threshold voltage (Vth) of the driving transistor may increase and a current flow may decrease. Also, as emission time of the organic light-emitting diode increases, an emission efficiency of the organic light-emitting diode may decrease. If these phenomena continue, a deterioration of image qualities may occur. Therefore, characteristics of the driving transistor and the organic light-emitting diode need to be accurately sensed and differences in these characteristics should be accurately compensated for.